Segmented stator ring assembly



Julyl9, 1960 c. E. HOCKERT ETAL 2,945,673

SEGMENTED STATOR RING ASSEMBLY Original Filed Oct. 51. 1951 2Sheets-Sheet 1 Uncntor:

W Qttorney c. E. HOCKERT ETAL 2,945,673

SEGMENTED STATOR RING ASSEMBLY Original Filed Oct. s1 1951 July 19, 19602 Sheets-Sheet 2 United States Patent SEGMENTED STATOR RING ASSEMBLYChester E. Hockert and Leslie R. Smith, Indianapolis, Ind., assignors toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareOriginal application Oct. 31, 1951, Ser. No. 254,143,

now Patent No. 2,772,069, dated Nov. 27, 1956. Divided and thisapplication Apr. 17, 1956, Ser. No. 578,654

1 Claim. (Cl. 253-78) This invention relates to engaging means fordetachably interconnecting a shrouded blade assembly of the segmentedring variety used in multistage fluid dynamic rotary machines and is adivision of application Serial No. 254,143, filed October 31, 1951, nowPatent No. 2,772,069.

From the standpoint of weight, simplicity of manufacture, and facilityof assembly and disassembly, ringlike blade assemblies composed of aplurality of interconnected annular segments aflord many advantages overthe type of blade assembly commonly employed heretofore composed of aplurality of circumferentially spaced blades or vanes positioned betweencontinuous outer and inner shroud rings. A shrouded blade assembly ofthe aforesaid segmented ring variety is illustrated and described inUnited States Patent 2,640,679, issued June 2, 1953, in the names ofJohn B. Wheatley, Arthur W. Gaubatz, and Charles C. Anderson, andassigned to the present assignee, wherein there is shown a stator ringstructure which comprises a pair of semi-circular ring vane assemblieseach of which is constituted by outer and inner shroud bands betweenwhich are mounted a plurality of stator vanes. Each of the inner shroudbands comprises a pair of concentrically disposed channel members havingsuperimposed webs and inwardly directed flanges which provide a fluidseal for reducing air leakage between the tips of the stator vanes andthe rotor of a turbine or axial-flow compressor.

The present invention is directed to novel engaging means for detachablyinterconnecting adjacent arcuate segments of a double-channel innershroud ring of a segmented stator ring structure.

The present invention has among its objects to provide simple andinexpensive engaging means for detachably interconnecting a segmentedblade assembly so as to facilitate rapid assembly and disassemblythereof and to positively interlock the stator ring segments againstmovement in a direction substantially transverse to the plane of theblade assembly, while accommodating or permitting longitudinal orperipheral movement due to differential thermal expansion of the ringsegments.

Other objects, together with the features and advantages of the presentinvention, will appear more fully from a consideration of the followingdetailed description and drawings wherein:

Fig. 1 is a fragmentary transverse view of a segmented stator vaneassembly utilizing an engaging means in accordance with the presentinvention;

Fig. 2 is .a' fragmentary sectional view taken in the plane indicated bythe line 22 of Fig. 1;

Fig. 3 is a fragmentary detail view of an engaging means in accordancewith one embodiment of the invens tion; 6 v

' Fig. 4 is a fragmentary axonometric view of the structure of'Fig. 3;

Fig. 4a is a modification of Fig. 4;

Fig. 5 is a fragmentary view of another embodiment of the presentinvention; and

, 2,945,673 Patented July 19, 1960.

Figs. 6 to 8, inclusive, are fragmentary axonometric views of stilldifferent embodiments of the present invention.

Referring to the drawings, Fig. 1 is a fragmentary transverse view of asegmented stator ring structure of a type suitable for use in an axialflow compressor or turbine of a gas turbine engine and the like. I

The stator ring structure 10 is contained within a cylindrical outercasing 11 composed of two half-sections to facilitate assembly anddisassembly thereof. The stator ring structure 10 comprises a pair ofsemi-circular segments 12 that correspond to the halves of the casing11. Each of the segments 12 is constituted by a semi-circular outershroud band 13 and inner shroud band 14 between which are secured aplurality of stator vanes 16. Each of the inner shroud bands 14comprises a pair of concentrically arranged channel members 18, 20 asshown in Fig. 2 and by the'axonometric view of Fig. 4, for example. Thechannel members provide a fluid seal that materially reduces leakage ofair around the stator vanes 16. The larger outer channels 18 comprise abase or web portion 22 and a pair of inwardly extending sealing flanges2 4, 26, the web portion 22 thereof serving as inner shroud bands whichmay project axially beyond the leading and trailing edges of the statorvanes '16. Each of the smaller inner channels 20 also com: prises a baseor Web portion 28 and a pair of inwardly extending sealing flanges 30, 32, the webs 22 of the larger channels 18 being superimposed orseated onthe webs 28 of the smaller channels 20 and may be rigidlysecuredthereto. as by spot welding, for example. The resultant series ofaxially spaced flanges 24, 30, 32 and 26 of the inner shroud band 14 areadapted to project into proximity to the surface of a rotor disk (notshown) as described in the aforementioned patent, thereby providing anelfective labyrinth seal. The sealing flanges can be of various lengthsor shapes, depending on the contour of the rotor .of the machine. v j

The shroud bands '13 and channels 18 and 20 constituting the innershroud bands 14 are preferably of rolled stock which possesses littleweight and suflicient rigidity. The outer and inner channelslS and 20'ofthe inner shroud bands are rigidly secured together before they arepierced to receive the tenons of the stator vanes and before theirterminal portions are shaped or cut off as will appear hereinafter. Whenassembled with the outer shroud bands and the stator vanes, the outerand inner channel members of the inner shroud bands serve both as areinforcing integral part of the stator ring structure and as a sealingdevice.

The outer shroud bands 13 extend circumferentially around the interiorof the compressor or turbine casing 11 and may be formed with outwardlyprojecting periph eral flanges or rims 34, 36 which are seated in anannular of the stator ring. The stator ring structure is supported fromthe interior of the split casing 11 by a plurality of spaced stud bolts44 extending through the casing to engage threaded bosses 45 fixed inthe outer shroud bands. 7

As illustrated in Fig. 2, the outboard and inboard ends of the statorvanes 16 are shaped to provide outer and inner projecting tangs ortenons 46, 48 which are received in radially aligned elongated apertures50, 52 circumferentially spaced about the periphery of the outer shroudThe casing 11 is constructed of two semibands .13 and the channelmembers 18 and 20 of the inner shroud bands 14 respectively. The tenons46, 48 are headed as illustrated by electric upsetting or other suitablemeans to rigidly securethe vanes 16 to the outer and inner shroud bands,and additionally fix the channels 18 and 20 together.

, The segments of the stator'ring structure 10 are interconnected bytongue and groove connections integrally formed at both ends of each ofthe inner shroud segments 14, as shown in Figs. 2, 3 and 4. As bestillustrated in Fig. 4, the inner channel 20 of one inner shroud band 14projects peripherally beyond the flanges 24, 26 of the outer channel 18and has a shallow groove or slot 54, defined by the surfaces at, b, c ofFig. 3, formed in the web 28 of one extremity thereof. The groove 54 isadapted to receive a complementary mating tongue 56 in slidableengagement therewith, the tongue being integrally formed in the web 28at the apposite extremity of the corresponding inner channel member 20of the inner shroud band 14 of the adjacent ring segment 12. The outerchannel 18 of the other shroud band 14 extends or projects similarlybeyond the flanges 30, 32 of the inner channel member 20 and has agroove or slot 58, defined by the surfaces d, e, f of Fig. 3, formed inthe web 22 thereof so as to slidably receive a complementary matingtongue 60 formed in the web 22 at the apposite extremity of the outerchannel member 18 of the first inner shroud band 14 of the firstmentioned ring segment.

When assembled in position, the junction between the opposed ends of apair of adjacent inner shroud bands is as illustrated in Fig. 3. Thetongues and grooves may be lengthened where space permits. Theperipheral separation X, Y between the ends of the outer and innerchannel members of the respective inner shroud band segments allows forcircumferential expansion, while the spacing between the edges of therespective tongues and their associated grooves prevents binding andaids assembly. Preferably, each channel of each inner shroud band isformed with a tongue at one end and a groove at the other end, so thateach segment 12 is identical with the other segments.

In order to insure easy entry of the tongue 60 above tongue 56 andthereby obviate misaligment and possible bending of the ring, theentering edges of the tongues and grooves may be chamfered approximatelyone-half the stock thickness as shown in Figs. 3 and 4. The enteringedges could be slightly curled in opposite directions in order to spreadthe tolerance and aid proper engagement, if desired, as shown in Fig.4:2, for example, in which the web 56 of the inner channel member of onering segment is oppositely curved to the web 60' of the outer channelmember of the other adjacent ring segment.

The tongues and grooves can be stamped out as integral parts of theouter and inner channel members of the inner shroud ring segments,thereby eliminating any welding or riveting operations sometimes usedfor fastening segmented shroud bands. The interlocking means thusprovided is not only simple and inexpensive to manufacture, but adds noweight to the stator ring structure.

It has been found that the segments of a segmented blade assemblyincorporating the tongue and groove fastening method of the presentinvention are self-positioning and that the ring structure lends itselfto circumferential expansion. The latter feature is particularlyadvantageous and desirable in a gas turbine engine wherein the hightemperatures attained could cause buckling of a continuous ringassembly. Once the ring assembly is assembled, the interengaging meansinsure a positive interlock against relative axial movement and yetpermit ready disassembly when necessary.

Figs. to 8, inclusive, illustrate different embodiments of theinvention. In Fig. 5, the web 28 of one end of the inner channel member20 of the shroud band 14 is recessed or cut back to allow the flanges30, 32 thereof to project peripherally beyond the end of the outerchannel member 18. The projecting flanges 30, 32 are oppositely curvedand flare outwardly as shown. The corresponding inner channel member 20of the mating band 14 also projects beyond the end of the outer channelmember 20 and has a notch 64 in the end of-the-web-28 thereof to permitthe flanges 30, 32 thereof to be curved inwardly so as to fit within theflanges of the first inner channel member 20 and to be positivelyinterlocked therewith when in the assembled position shown.

In the form of Fig. 6, one end only of the inner channel member 20projects beyond the outer channel 18. The web 28 and flanges 30 and 32of the projecting end are bent inwardly so as to fit within theunmodified end and to be'received between the flanges of the innerchannel of the adjacent section.

In a preferred form of the invention illustrated in Fig. 7, a projectingtab 68, welded or otherwise fixed to the web 28 of one inner channelmember 20, slidably-engages the inner surface of the web 28 between theflanges 30, 32 of the other inner channel member 20 and provides apositive axial interlock therebetween. In addition to centering andlocking adjacent ring segments against relative axial movement, the tabalso permits relative circumferential or longitudinal movement of thering segments due to differential thermal expansion peripherallythereof.

In the form of Fig. 8, a pair of projecting tabs or fingers 70, 72having curved ends are welded or otherwise secured to the outer surfacesof the flanges 30, 32 of the inner channel member 20 and/or to the innersurfaces of the flanges 24, 26 of the outer channel member and areslidably received between the outer surfaces of the flanges 30 and 32 ofthe inner channel member 20 and the flanges 14 and 18 of the outerchannel of the inner shroud band of the adjacent ring segment. Inaddition to providing some sealing action of the mechanical clearancespace between the adjacent ends of the ring segments, the arrangement ofFig. 8 also provides the function and advantages of that shown in Fig.7.

It is to be understood that the above-described arrangements areillustrative of the application of the principles of the invention.Numerous other arrangements may be devised without departing from thespirit and scope of the invention.

What is claimed is:

A segmented stator ring structure for a fluid machine of the dynamictype comprising, in combination, a plurality of arcuate bands arrangedto form a segmented outer ring, a plurality of arcuate bands arranged toform a segmented inner ring substantially concentric with said outerring, and a plurality of stator vanes mounted between the bands of saidouter and inner rings, each of the bands of said inner ring comprisingan outer channel member and an inner channel member concentric with saidouter channel member, said channel members having superimposed websconnecting inwardly directed flanges, the flanges of said outer channelbeing spaced more than a predetermined distance from the correspondingflanges of said inner channel, and means for detachably interconnectingadjacent bands of said inner ring, said interconnecting means includinga pair of projecting fingers secured to and located betweencorresponding flanges of the outer and inner channel members of an innerring band, said fingers being received in the predetermined spacebetween the corresponding flanges of the outer and inner channel membersat the apposed extremity of the channel member of an adjacent inner ringband, said fingers having a width less than said predetermined distancebetween corresponding flanges of said inner and outer channel members,whereby said fingers will interconnect said adjacent bands even throughthe corresponding flanges of the adjacent bands are not exactly ali ed.

(References on following page) References Cited in the file of thipatent UNITED STATES PATENTS Clarke Sept. 13, 1910 Schmidt Mar. 7, 1911Owen et a1 Sept. 23, 1913 Gilson Dec. 3, 1918 Moore May 27, 1919 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,945 673 July19 1960 Chester E. Hockert et a1,

It is hereby certified that error appears in the-printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 2 line 23,, for "portion" read portions column 4 line 71 for"through" read though --5 column 5 line 6 list of references cited underUNITED'STATES PAJFEBIFS" for the patent number "2 286 283" read 1,286,383 line T for "2 304 793" read 1,304 793 Signed and sealed this20th day of December 1960o (SEAL) Attest:

KARL. H0. AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner ofPatents

